I was so seriously disappointed by this. From most of the things I'd read about it, I was expecting a few decent scares, an interesting, gripping storyline and a great atmosphere. For me, it didn't really deliver on any of those points.
The acting was good, I can't deny that. But the scares were so cheap you could see them coming a mile off, not one of them actually got me. And there was just no tension or atmosphere to speak of. I could see they were trying to build it, in the scenes where Ethan Hawke was walking down darkened corridors of his house, or going up to the attic. But it was tired and old, and just failed at building any palpable fear at all.
Then the storyline. As Ghosty said above, I found it illogical and rather than get caught up in it, I was questioning why they would do certain things, and why the 'demon' would just choose to kill them if they moved house. Made no sense to me.
It didn't seem to know what it wanted to be, crime/suspense thriller, serial killer flick, supernatural. It felt like it flitted around all the time, when maybe if it had picked one track and stuck to it it would have been much better.
The base idea of the serial killer was decent enough, and I thought the inclusion of the snuff films was a good angle, and those bits were well made, but they didn't make enough of the good things the film had, and instead tried to inflict poor, dated scares on the audience.
Oh and the demon? I laughed when I saw it! I've seen scarier Disney villains. Cruella De Ville anyone? About 1500 times scarier than that thing.
I'd give it 4/10. It might seem like I'm being a little harsh on the film, but I think it's because I was really looking forward to this and hoping it was going to be scary, something like Insidious. It disappointed me big style.